1. Field of the Invention
The present invention relates to an optical module that provides a plurality of optical assemblies, some of which are precisely assembled even in perpendicular to an axis of an optical fiber.
2. Related Background Arts
A bi-directional optical module, which provides an optical subassembly to transmit an optical signal to and another optical subassembly to receive an optical signal from a single fiber, has been well known. FIG. 6 is a plan view of such a bi-directional optical module 101, where the optical module 101 provides two transmitter subassemblies, 103 and 104, a receiver subassembly 102, and some other optical components, 106 to 108, set in a housing 109.
One of optical transmitter subassemblies 104 aligns the optical axis thereof with that C of the optical fiber 105a; while, the other of the transmitter subassemblies 103 has the optical axis D2 perpendicular to that C of the optical fiber 105a. Those optical subassemblies, 103 and 104, are fixed to the housing 109 after the optical alignment with respect to the optical fiber 105a is carried out. The optical alignment of one of the transmitter subassemblies 104 in a plane perpendicular to the optical axis C is simply carried out because this transmitter subassembly 104 has the optical axis common to that of the optical fiber 105a. However, the optical alignment of the other of the transmitter subassemblies 103 has the optical axis D2 perpendicular to the optical axis C is complicated because, not only the optical axis D2 is perpendicular to that C of the optical fiber 105a, but the housing 109 has a shape asymmetric with respect to the axis D2.
When an optical component has a cylindrical or pillar shape, such as optical subassemblies, 102 to 104; an apparatus for performing the optical alignment and then fixation as maintaining the aligned status of the components can easily pick such an optical component as keeping the positional accuracy thereof, namely, aligned status of the component by, for example, a chuck. However, the housing 109 generally has a complex shape because, in a case of a bi-directional optical module, the housing 109 installs optical components of WDM filters, 107 and 108, and a lens 106 therein. For such deformed housing, specifically, an asymmetric shape with respect to the optical axis D2 of the optical subassembly 103, it is quite hard to realize the precise optical alignment of the optical subassembly 103 because the apparatus, or the chuck, cannot hold the housing 109 stably during the alignment and the fixation.